Generally, a coiler refers to an apparatus that winds a predetermined amount of coil corresponding to a sheet-shaped plate and an uncoiler refers to an apparatus that unwinds the wound coil contrary to the coiler.
In order to easily wrap and unwrap a coil, known uncoiler apparatus utilize a drum that applies outward pressure to the inner surface of the coil. As the coil is wound on the drum, the coil is clamped by the outward pressure of the drum about which it is placed. When the coil is pulled, the coil rotates with and is unwound from the drum. When the drum stops rotating, the clamping force of the drum prevents the coil from unwinding further.
Such coiler apparatus ensure positive engagement through application of a single, high clamping force. Because a single, fixed clamping force is applied in all cases, the clamping force in individual applications tends to be higher than necessary.
Excessive pressure applied by the drum on the coil damages the part of the coil in contact with the drum at the inner periphery of the coil. Because of the damage to the surface of the coil, a significant amount (e.g. 20%) of the total amount of the coil is wasted.
What is needed is an uncoiler apparatus that allows for coiling and uncoiling while overcoming the above-mentioned disadvantages.